The index is based on contract signings (with sales usually finalized one or two months later) and is benchmarked to 2001 contract activity. (An index of 100 is equal to the average level of contract activity during 2001, which was the first year the association examined data).

With these newest numbers in, home contract activity is at a three-year high and is 10.3% above April 2012's reading.

Despite small national gains and month-to-month declines in the West (7.6%) and South (1.1%), NAR Chief Economist Lawrence Yun remains positive about the housing recovery. "The housing market continues to squeak out gains from already very positive conditions," he said. According to NAR's calculations, existing home sales are expected to increase 7% this year, while a supply squeeze will push the median price up 8% to over $190,000.